Advanced Technology Corporation, Oak Ridge, Tennessee, USA.
Structural integrity and operational efficiency of metallic structures such as oil and gas pipelines, pressure vessels, ship structures, and bridges degrade with aging and service conditions. Continued safe operation of these structures requires periodic examination of their current physical condition (with respect to the existence of flaws/cracks) and their actual mechanical properties. Until late 1980s, advances in physics and materials science focused on non-destructive testing (NDT) techniques to detect and size flaws, cracks, corrosion pitting, stress corrosion cracking, and reduction in thickness, while there were no NDT methods or instruments to determine the key mechanical properties (namely, tensile and fracture toughness) of inservice structures. Old techniques involved the extraction of boat samples or hot-tapping to machine destructive specimens. These undesirable/unaccepted techniques result in expensive loss of service and require some repair actions. The new Portable/In-Situ Stress-Strain Microprobe® (SSM) system was invented in 1989 to fill this gap for numerous industries by providing nondestructive and in-situ/field capability to measure the required mechanical properties. Applications of the innovative SSM system, that utilizes nondestructive Automated Ball Indentation (ABI) test techniques to determine tensile and fracture toughness of in-service steel pipelines, are described in this paper.
